1. Field of the Invention
This invention relates to halogen scavengers, and more specifically to halogen scavengers capable of suppressing the release of halogen gas harmful for the human body.
2. Description of the Related Art
Halogen gas such as chlorine gas, which is released by various chemical reactions, have extremely harmful effects on the human body. There is hence an outstanding demand for the suppression of its release.
Hypochlorites such as sodium hypochlorite, for instance, are used in bleaching agents such as bleaching agents for clothes, bleaching agents for kitchen use, mold removers, toilet cleaners, drain pipe cleaners and disinfecting cleaners. These hypochlorites, however, give off toxic chlorine gas under the action of an acid so that their combined use with an acid cleaner has been extremely dangerous.
In fact, there have been reported several accidents caused by the use of a mold remover and an acid cleaner in combination. Bleaching cleaners containing sodium hypochlorite or the like and acid cleaners containing hydrochloric acid or the like are now required to show the warning note, "Dangerous. Don't mix ".
In the case of acid cleaners containing hydrochloric acid, hydrogen chloride changes to chlorine gas in an oxidative atmosphere. A working compartment with a drafting equipment is therefore provided for the handling of an industrial acid cleaner where release of chlorine gas is expected. It is, however, difficult to take such a measure for the domestic use.
In addition, it has become necessary to adopt an effective means for the removal of halogen so that the air in halogen-handling research or production facilities can be cleaned or resins can be produced with improved properties.
For the purposes described above, there have heretofore been proposed as halogen scavengers sulfamic acid, resorcine, pyrroglutamic acid (Japanese Patent Publication No. 56154/1985), catechins (Japanese Patent Publication No. 18909/1990), boron and iodine compounds (Japanese Patent Publication No. 10178/1990), isocyanuric acid (Japanese Patent Laid-Open No. 58328/1989), tetrathiafulvalene (Japanese Patent Laid-Open No. 171624/1989) and quaternary ammonium salts (Japanese Patent Laid-Open No. 56599/1991).
In addition, scavengers disclosed in patent publications include 2-methyl-2-butene, pinene (Japanese Patent Laid-Open No. 142137/1987) and, as substances capable of binding halogen, phenol, nylon, polyacetylene and tetrathiafulvalene derivatives (Japanese Patent Laid-Open No. 171624/1989).
Almost all these halogen scavengers, however, are intended to capture chlorine present in a solution or that to be released gradually in a solution. For chlorine gas to be released abruptly as in the case of mixing of a chlorine-base bleaching agent with an acid cleaner, absolutely no scavenger has been known yet to promptly capture it before its release into the air except for quaternary ammonium salts.
It is known, on the other hand, that many aromatic compounds form charge transfer complexes together with halogen. Substances capable of forming charge transfer complexes together with halogen, however, have not been studied too much with respect to their effectiveness for the capture or absorption of halogen. Among these substances, only tetrathiafulvalene is regarded to scavenge halogen selectively and effectively (Japanese Patent Laid-Open No. 171624/1989).